Mercury-vapor rectifier



Nov. 11, 1930. J. KUBLER ET AL MERCURY VAPOR RECTIFIER Filed Febv 16.1929 Fig. 7.

Fig. 2.

Inventor's Johannes Kubler Ernst Kobe! Patented Nov. 11,1930

JOHANNES KUIBLER, or BADEiN, AND Emvsr ascent, or statesmen,swrrznarinnn MER URY-Verde iinc'irrrinia Application filed February 16,19 29, Serial No. in setting January 30,

This invention relates to improvements in metallic vapor electriccurrent rectifiers and,

it particularly, to the cathode constriiction thereof and to means forpreventing 5 the formation o'fexcessi've amounts of vapor therein. I

It wellkno'wn that occurrence'of the condition commonly called shortcircuiti ng, which results iromcurrent flowing be tween seja eaesmodesot' an electric current rectifying structure 'rhther than between ananode and the cathode thereof may be caused by the formation ofexcessive quantities of metallic vapor which condense on the anode toproduce a spot having the characteristics of the cathode. It is,therefore, desirable that the formation of excessive quantities ofmetallic vapor, i. e., amounts greater than necessary to conduct anelectric are between the electrodes be prevented to avoid shortcircuiting or so'called backfiring Within the rectifier. One of thecauses leading to the formation of excessive amounts of metallic vaporis the action of the electric are which travels over the surface of thecathode with cmisiderable rapidity thereby heating the entire surface ofthe cathode above the vaporization point of the material used. Variousattempts have been made to prevent such rapid movement of the arc withthe attendant heating of the cathode by providing means for fixing theare at some particular point on the cathode. Among the means proposedhas been the provision of structures formed from materials having anespecially high melting point and arranged Within or adjacent to thecathode material, which means, in themselves, are not satisfactory.Gontinuous researchinto the causes and the means for preventing shortcircuiting, above referred to, have shown that the amount of metallicvapor produced may be reduced in a very large degree without fixing thearc.

It is, therefore, among the ob ects of the present invention to providemeans for preventingthe formation of an excessive amount I of metallicvapor within an electric current rectifier without the provision of anymeans for fixing the arc.

Another object of the inventlon 1s to proll'ieajns for cooling thesurface of the catl'iode material so that tormation of the metallicvapor from the free cathode surfaces, with the exception of the point ofat tachment of the are, is so far prevented that the cathode snrta'ceserves as a condenser for the vaperaliead prdduced.

Objects and advantages, other than those above set foith, will bereadily apparent from the description and the drawings in which Figure 1is a partial cross-sectional View of a metallic vapor electric currentrectifier en'ibodyir'ig the present inventioii, and

Fig; 2 is a View similar to that shown in Fig.1 but illustrating amodified form of the invention. a a 3 more particularly to the drawbycliarztct'ers of reference, cathode 5 connitohly eenipnsin mercury isretained within a cbn'tainer form'ed by instilating porai ab ont anaperture in the teaoinptrcion 7 of a rectifier tank and dependingtherefrom. The space iiiclosed by the insulating wallsh is shnt' on by abottom plate :8 which, according to the present inve ues, is t cirmed toprovide a chamber therein. A condiiit 9 meaning through the bhttom plate8 id coiinected with a coil of tubihg" 10 is connected to a schrceofsupply for a cooling flii'id' (not shown) which' is circulated through@1 It) and returned to the cl iamber within pl'a by a connection 11 hrwhich chamber the cobling fluid is dis gen by a distlmg'e coiiduit 12.To obchar V tain aiid uiiitorm' heat transfer from the cathodemercnryfithe coil 10 is preferably fornx dbof material having a highheat con- ;luct1v1 ty coetficih-nt such as copper, which may be coatedwith a non-amalgamable material subs chromium. In order, further, to piote'ct the coilltl from contact therewith or attachment: thereon theelectric are, a shielding plate 13 is arranged to rest upontl'iejcooling coil 10 ,which thereforelocates 9r plate 13 just below thesurface of the cathode mercury. The shield 13 fully protects the coil 10from occasional or accidental penetration of the electric arc tllIOllgllthe cathode mercury 5 and ispreferably formed of some difiicultlyfusible material which does not form an amalgam with mercury. Instead offorming the cooling means, as

I. above described, as of a coil of tubing arranged within the cathode,the coil of tubing may be omitted, thereby decreasing the amountofmercury requiredfor the cathode, as is shown in Fig. 2. When the coolingcoil 10 is omitted, it isdesirable that the protecting shield 13 bearranged immediately about I the'upper surface ofthe closure'member e pa ninlet 9.

dispensed with if the bottom plate 8 is made which is supplied withcooling fluids through The shield member 13 may be of some materialhaving a high melting point. If desired, the bottom plate be made of 7some material having a relatively low melt- 1 ing point such asiron,.provided with pro-v jecti ons' ofsome difiicultly fusible materialextending into themercury to furnish points to which the are may becomeattached but in any event the portion thereof in contact wlth thecathode material shouldbe of material havinga high rate ofheatconductivity.

the center of the cathode are cooled.

Itwill usually be found that water is .adequate for coolingpurposes butin case a more intensive cooling of the cathode is desired, it will beunderstood that other cooling orrefrigerating means may be supplied tothe chamber within plate 8 and to the cooling coil in such manner thatthe surface of the mercury is cooled far below the vaporization pointthereof and is thereby adapted to operate as a condenser for thoseportions of the mercury vaporcoming into contact therewith.

metallic vapor type, a liquid metallic cathode,

a cooling device arranged within said cathode to provide a path for thecirculation of a cooling medium therethrough said cooling device'beingcomposed of a material having high heat conductivity, and a shieldingplate of dilficultly fusible material arranged intermediate the uppersurface of 'said cathode and said cooling means to prevent attachment"ofthe electric arc thereon.

metallic vapor type, a liquid metallic cathode,

. V I '75 Y 4. In an electric current rectlfier of the a coil of tubingcomposed of a material hav- 1 mg. hlgh heat conductlvlty and arrangedWithin said cathode to provide a path for the circulation of the coolingmedium therethrough, and a shielding plate of difficultly fusiblematerial arranged intermediate the upper surface of said cathode andsaid coolmg means to prevent attachment of the electric arc thereon.

In testimony whereof we have hereunto subscribed our namesthis 8th dayofJanuarmanieaa JOHANNES KUBLERJ,

. enusrnoenn:

to provide path for the circulation of a V cooling mediumtherethrough,and a shieldmg plate of .difiicultly fusible material arrangedintermediate the upper surface of said cathode and said cooling means topre vent attachment of the electric arc thereon.

2. In an electric current rectifier of the V metallicvapor type, aliquid metallic cathode,

a cooling device'arranged within saidcathode to provide a path'for thecirculation-of a cooling medium therethrough, and a shieldingplate ofdifficultly fusible material an ranged intermediate'the upper surface ofsaid cathode and said cooling device to prevent attachment of theelectric arc thereon.

3. In an electr1c current rectlfier of the

